Operating mechanism for a furniture part including a shape memory element

ABSTRACT

In an operating mechanism for a moving a furniture part via a drive arrangement including a shape memory element, the shape memory element is connected between a stationary support point and a part to be moved via a force- or form-locking coupling structure having a limited holding force to prevent over-stressing the shape memory element.

This is a Continuation-In-Part Application of pending international patent application PCT/DE2009/000927 filed Jul. 2, 2007 and claiming the priority of German patent application 10 2008 030 933.8 filed Jul. 2, 2008.

BACKGROUND OF THE INVENTION

The invention resides in an operating mechanism for moving a furniture part, that is movable with respect to a stationary furniture part by means of a drive arrangement including a shape memory element toward an opening position or a closed position. The drive arrangement is mounted to one furniture part and abuts the other furniture part by way of a coupling element. The drive arrangement includes as drive element a shape memory element which shrinks upon heating and which is arranged between the coupling element and a fixed support location opposite the drive arrangement.

DE 10 2008 027 541 discloses such an operating mechanism for example for opening drawers and furniture doors.

It is the object of the present invention to provide an operating mechanism for opening or closing furniture parts including a drive structure which includes at least one shape memory element wherein however the shape memory element actuating the drive structure is protected from overload by faulty or erroneous operation.

SUMMARY OF THE INVENTION

In an operating mechanism for a moving a furniture part via a drive arrangement including a shape memory element, the shape memory element is connected between a stationary support point and a part to be moved via a force- or form-locking coupling structure having a limited holding force to prevent over-stressing the shape memory element.

In the operating mechanism according to the invention includes a drive arrangement wherein an operating force is generated by one or more shape memory elements providing for a certain linear movement. The linear movement is transmitted directly, or by way of a drive structure, to the furniture part which is movably supported by the stationary furniture part on which the movable furniture part is supported and which carries the drive arrangement. The shape memory element or elements may be one or several times re-directed by pulleys or guide tracks.

The drive arrangement of the operating mechanism may be for example a lever drive, a gear drive a gear rack drive or a similar device.

For obtaining a linear stroke which acts counter to the actuating stroke of a shape memory element for example a spring drive, a gravity drive or a second shape memory element may be used.

The stationary parts of a furniture piece are for example the cabinet body, the desk body or also a door frame. The movable furniture parts are drawers, sliding doors, revolving doors or pivot doors, flaps, extendables, or other movable parts which are moved or pivoted out of the stationary furniture piece for a certain purpose.

The drive arrangement is generally attached to the stationary furniture part. But it is also possible to attach the drive arrangement to the movable furniture part for moving the movable part away from the stationary part.

The shape memory elements which provide for a linear movement and which are used for example for the opening of drawers may be arranged in the furniture body on the side, behind, above or below the drawer. Their longitudinal orientation may be aligned with, transverse or inclined to, the direction of movement of the drawer. The shape memory elements may be arranged along the back wall along several drawers vertically or diagonally with respect to the furniture body.

The shape memory element in the form as a central drive element is subjected to high stresses if the operating stroke is inhibited or blocked during operation. In order to prevent an overload of the shape memory element, it is supported on the stationary furniture part or the opening and closing mechanisms of the movable furniture part by way of a coupling which opens depending on the force applied thereto.

This coupling may be a force-locking coupling in the form of a magnetic clutch. Herein the two parts being connected may be coupled by permanent magnetic or electromagnetic forces. Also a form-locking coupling in the form of a symmetric or asymmetric engagement lock may be used which engages in a force-locking and form-locking manner.

Further features of the invention will become apparent from the following description of a particular embodiment thereof described below with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a drive arrangement with a pull wire drive operating by way of a bent operating lever with the drawer closed,

FIG. 2 is an enlarged view of the housing of FIG. 1,

FIG. 3 shows an operating carriage of FIG. 1 in an enlarged view,

FIG. 4 shows a guide carriage of FIG. 1 in an enlarged view,

FIG. 5 shows an operating arm of FIG. 1 in an enlarged view,

FIG. 6 is a view as shown in FIG. 1 but with a drawer opening arm pivoted, and

FIG. 7 is a view as shown in FIG. 6 but with the opening arm pivoted back,

FIG. 8 is a view as shown in FIG. 1 but with the opening arm pushing open,

FIG. 9 is a view as shown in FIG. 8 immediately after a blocking of the opening stroke of the drawer,

FIG. 10 shows a magnetic clutch with a rubber damper in an open state,

FIG. 11 shows a magnetic clutch with a pneumatic damper in an open state,

FIG. 12 shows an arrangement like FIG. 11 but in a closed state,

FIG. 13 shows an engagement clutch in a closed state, and

FIG. 14 shows an engagement clutch in an open state.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT

FIG. 1 shows an operating mechanism for electrically opening a drawer 21 of a cabinet 10 wherein the drive arrangement 230 includes as drive element for example a special pull wire 91. The pull wire 91 consists of a shape memory alloy, for example, a nickel-titanium alloy. This alloy has for example a so-called intrinsic two-way effect, that is, the pull wire can remember two shapes—one it assumes at high temperature and another one it assumes at low temperature. The pull wire 91 can therefore switch back and forth solely on the basis of a temperature change between a stretched cold shape and a shortened warm shape. For heating, the pull wire 91 is electrically energized shortly via its ends. The electric connecting wires are not shown in the drawings.

An individual pull wire has in the exemplary embodiment shown herein a round cross-section and for example a diameter of 0.5 mm. The pull wire cross-section may also have an oval, square, rectangular elliptical star- or V-shape or any other possible cross-sectional shape.

The housing 231 shown in FIGS. 1 to 9 in an open state is for example in the form of a cylindrical container with for example a planar bottom 245 and four planar walls. In the housing 231 in which, among other items, two carriages 250, 260, an opening lever 270 and two tension springs 241, 249 are supported, a guide frame 232 with a recess 233 and a spring support structure 245 are arranged on the housing bottom 245, see also FIG. 2.

During operation, the housing 231 in closed by a cover which is mirror-reversed with respect to the housing bottom 246 and also includes a guide frame 232 and a recess 233.

The operating carriage 250 which is disposed in the guide frame 232 so as to be longitudinally movable is shown in FIG. 3 in a central cross-sectional view. The operating carriage 250 consists essentially of an upper and a lower plate which plates are interconnected by an at least essentially U-shaped web 251 so that the operating carriage 250 has an opening oriented toward the opening lever 270. The longitudinal side of the operating carriage 250 forms a gear rack 252. The right front side of the operating carriage 250 has a cavity forming a support location 253. The operating carriage has a back wall 254 with a dead end bore 255 into which for example a permanent magnet 31 is cemented.

As shown in FIG. 1, at the left next to the operating carriage 250, a guide carriage 260 of comparable design is arranged which is disposed also in the guide frame 232. It also consists of for example parallel plates which are interconnected by a U-shaped web 261. However, its opening is oriented toward the rear wall 12 of the furniture body. See FIG. 1. In the upper and lower plate of the guide carriage 260, see FIG. 4, there is an L-shaped elongated guide opening 264 whose larger straight center line section extends in the extension of the straight developing line of the gear rack 252 of the operating carriage 250. The short area of the elongated guide opening 264 which is angled in the drawer opening direction 1 is at least long enough that its left push flank 265 has a straight section of a length of several tenths of a millimeter.

The guide carriage 260 includes as part of the web 261 a front wall 262 with a dead-end bore 263. In the dead end bore 263, there is for example a magnet 32 or a magnetic plate mounted by cementing or clamping or by any other mounting means. For example, the cylindrical magnet 32 whose centerline extends parallel to the direction of movement of the guide carriage is aligned with the magnet 31 of the operating carriage 250. The centers (of gravity) of the magnet poles are disposed on the center lines of the magnets. The north pole of the one magnet 31 is disposed opposite the south pole of the other magnet 32. As shown in FIGS. 1, 6, 7 and 8, the carriages are coupled together by the magnets 31, 32 in a force-locking manner.

FIG. 5 shows in a horizontal sectional view a push pawl 266 arranged and guided in the elongated guide opening 264 of the guide carriage 260 together with a pull clip attached to the pawl 266. The push pawl 266 includes a lever member 267 which projects therefrom sidewardly under an angle of for example 100° and is provided at its free end with a support structure 248 for a tension spring 249. This end projects sidewardly from the opening of the guide carriage 260. In the area of the jointure of the push pawl 266 and the lever member 267, there is a slot through which a guide pin 269 extends on which a pull member 92 is supported to which the pull wire 91 is attached.

The pull member 92 is supported by the guide pin 269. The guide pin 269 projects at the top and the bottom so far from the push pawl 266 that it is safely guided in the two elongated guide openings 264 of the housing 231. At the front end of the slide arm 266, there is a control pin 268 which extends parallel to the guide pin 269 and which extends through the elongated guide opening 264 and into the recesses 233 of the housing 231.

The opening lever 270 has an essentially disc-like hub 272 and a sickle-shaped curved long arm 271, see FIG. 1. The hub 272 has a partial gear structure 273 which faces away from the arm 271 and whose for example six teeth project from the hub 272 over for example 180°. In the center of the hub, the pivot bolt 276 of the opening lever 270 is arranged. The arm 271 has, opposite the rear wall 22, a curved contact surface 277 wherein the curvature corresponds for example to a section of a cylindrical sleeve, see FIG. 1. This contact surface 277 comes into contact during opening of the drawer 21 with the rear wall 22 of the drawer along a first line of contact 278. As a result, the opening lever 270 acts on the drawer 21 at the beginning of the opening movement for example with a lever arm which is shortened by about one half. Shortly before the outwardly moving drawer 21 leaves the opening lever 270, it is in contact with the opening lever 270 along the last line of contact 279. The opening lever 270 then acts on the drawer with its maximum lever arm length. If the contact arm surface has also a curvature transverse to the curvature as shown in FIG. 1, that is, if the contact surface is spherically curved the contact lines 278-279 became contact points.

For opening the drawer 21, the drawer is pressed with its rear wall 22 in the closing direction against the switch 8, see FIG. 9. The switch 8 energizes the pull wire 91 via an electrical or electronic circuit. As a result, the pull wire 91, which is connected to a support frame 15 the furniture body at a support point 237, and, via a pull connector 92 to the pull lever 266, see FIG. 1, is tensioned. In FIG. 1, the push pawl 266 is at this point in its right hand end position within the elongated guide opening 264 of the guide carriage 260 disposed at the right in the guide frame 232. The control pin 268 abuts the engagement flank 265 of the elongated guide opening 264. In this position, it is held by the tension spring 249. As the pull wire 91 becomes shorter, it pulls the combination of the push pawl 266, the guide carriage 260 and the operating carriage 250 to the left. In the process, the gear structure 273 of the opening lever 270 which is pivotally supported in the housing 231 at the pivotal support structure 275, rolls off the operating carriage 250. The opening lever 270 is pivoted thereby clockwise, see FIG. 8, against the rear wall 22 and as a result accelerates the drawer 21 in the opening direction 1.

Shortly before the opening lever has reached its end position as shown in FIG. 6, the control pin 268 abuts the inclined flank 234 of the recess 233 of the housing, see also FIG. 2. In this way, the control pin 268 is pushed off the engagement flank 265. The push lever 266 pivots thereby clockwise around the guide pin 269 by for example 13.5° so that the control pin 268 is moved in the area of the elongated guide opening 264 which extends parallel to the movement direction of the operating carriage 250. As a result, the joint guide carriage 260 and operating carriage 250 are uncoupled from the pull wire 91.

Then the operating carriage 250 and the guide carriage 260 are moved by the pull forces of the spring 24 toward the right, whereby the opening lever 270 pivots back, see FIG. 7. Herein, the push pawl 266 is not moved along.

During the following extension phase of the pull wire 91, the tension spring 249 attached to the lever arm 267 results in a displacement of the push pawl 266 toward the right. As soon as the pull wire has cooled down, the control pin 268 is again disposed in front of the engagement flank 265 for re-coupling the operating carriage 250 to the pull wire 91, see FIG. 1.

Upon closing the drawer 21, the operating mechanism is again in its original position.

FIG. 8 shows the operating mechanism during opening of the drawer 21. The energized pull wire 91 pulls the guide carriage 260 forcefully to the left. It is magnetically coupled to the operating carriage 550. The opening lever 270 rolls off the geared rod 252. It is pivoted already by 30° and slides along the back wall of the drawer 21 while accelerating the drawer 21 in opening direction.

Now the movement of the drawer is braked abruptly. This may occur when the opening drawer 21 abuts for example an external object or is stopped by an operator. This causes in the pull wire 91, which becomes shorter as a result of the earlier energization, to an excessive tension force. As soon as this tension force reaches the force required for opening the coupling 30, the magnets 31, 32 are disconnected. Then the guide carriage 260 moves to the left further tensioning the spring 249 whereas the guide carriage 250, driven by the tension spring 241, moves rapidly to the right while pivoting the opening lever 270 rapidly back, see FIG. 9, until it has reached its original position as shown in FIG. 7. As a result, the drawer 21 can then move back into its closing position without any restrictions.

As the pull wire 91 cools down and becomes longer, it is pulled by the tension spring 249 via the push pawl 266 to the right. Herein, the control pin 268 carries the guide carriage 260 along by via the elongated guide opening 264. When the pull wire 91 has cooled down the magnets 31 and 32 come again in contact with each other. The coupling is again closed. Now the arrangement is ready for another drawer opening procedure.

It is possible to prevent a premature energization of the pull wire 91 by monitoring for example the end position of the guide carriage 260 as it is shown in FIGS. 1 and 7 by a sensor. The sensor which may be for example a mechanical end switch, a contact-free magnetic reed switch or a light barrier determines the end position of the lever member 267 of the push pawl 266. If the sensor does not recognize the right end position of the lever member 267, the energization of the pull wire 91 is prevented.

In accordance with FIGS. 11 and 12, the last tenths millimeters of the coupling stroke are pneumatically braked. In this exemplary embodiment at the operating carriage 250, the cylindrical magnet 131 opposite the magnet 31 of FIG. 10 is elongated and at the guide carriage the magnet 32 of FIG. 10 is replaced by a thin magnetizable iron plate 132. The latter may of course also be manufactured of a magnetic material. Additionally, the dead end bore 263 is so far extended that for the magnet 131 a several mm long immersion path for the coupling procedure is provided. The dead end bore 263 becomes wider in the direction toward the operating carriage 250 so that it is slightly funnel-shaped.

Upon engagement of the force-locking magnetic coupling 130, see FIG. 12, the magnet 131 enters the dead end bore 263 and displaces from the narrowing bore 263 the air enclosed therein. In this way, the coupling movement is braked similar to the piston end position damping.

FIGS. 13 and 14 show a form-locking asymmetrically acting engagement coupling 330 via which the carriages 250 and 260 are coupled together. The engagement coupling 330 in the form of an engagement structure has an engagement pin 331 formed on the front wall 262 of the guide carriage 260. The engagement pin 331 comprises for example two elastic hooks which, with engagement coupling 330 activated, engage into for example a funnel shaped narrowing bore 337 in the rear wall of the operating carriage 250. The back wall 254 with the bore 337 forms the blocking structure 336 for the engagement coupling 330.

The hooks of the engagement pin 331 have an engagement flank 333 and a locking flank 332. With the engagement coupling 330 coupled the locking flank 332, which projects at an angle of 45° abuts the bore 337 walls at a 45° face angle. The engagement flank 333 extends at an angle of 15° with respect to the engagement direction 339. This small angle is intended to keep the coupling resistance small whereas the 45° angle of the locking flank 322 provides for a relatively large holding force.

The couplings 30, 130 and 330 are arranged in the exemplary embodiments between the pull wire 91 and the operating carriage 250. However, the couplings 30, 130 and 330 may also be positioned between the pull wire 91 and the body-side support point 237. It is also possible to integrate the couplings 30, 130, 330 into the pull wire 91 if they include also a guide system and spring element for the closing movement.

For opening the drawer 21, the switch 8 actuated by a closing movement may be replaced by an operating element which is arranged on the body 11, the drawer 21 or another suitable location. Also, a wireless operating arrangement is possible.

REFERENCE NUMERALS

1 Opening direction 2 Closing direction 8 Switch 10 Cabinet bottom part 11 Cabinet body 12 Rear wall of furniture 15 Support frame 21 Drawer, furniture piece 22 Rear wall of drawer 30 Coupling 31 Permanent magnet 32 Magnet, magnetizable plate 35 Dead end bore 36 Elastomer body damper 91 Pull wire shop memory element 92 Pull pawl 130 Magnetic coupling 131 Cylinder magnet 132 Magnetizable iron plate 230 Drive arrangement 231 Housing with cover 232 Guide frame 233 Recess 234 Inclined flank 235 Opening 236 Opening 237 Support point 238 Support point 239 Support point 241 Spiral tension spring 245 Housing bottom 246 Spring support structure 248 Support structure 249 Tension spring 250 Operating carriage 251 U-shaped web 252 Gear rack 253 Support location 254 Back wall 255 Dead end bore 260 Guide carriage 261 U-shaped web 262 Front wall 263 Dead end bore 264 Elongated guide opening 265 Push flank, engagement flank 266 Push pawl 267 Lever member 268 Control pin 269 Guide pin 270 Opening lever 271 Curved arm 272 Hub 273 Partial gear structure 275 Pivotal support structure 276 Pivot bolt 277 Contact surface 278 First line contact 279 Last line of contact 330 Engagement coupling 331 Engagement pin 332 Locking flank 333 Engagement flank 334 Free space 336 Blocking structure 337 bore 339 Engagement direction 

1. An operating mechanism for moving a movable furniture part (21) relative to a stationary furniture part (11), comprising: a drive arrangement (230) including a shape memory element (91) for initiating movement of the movable furniture part (21), said drive arrangement (230) being fixed to one of the furniture parts (11, 21) and abutting the other furniture part (21, 11) via a coupling element (270) and including the shape memory element (91) as drive element arranged between the coupling element (270) and a stationary support point (237), the shape memory element (91) being connected to at least one of the coupling element (270) and the stationary support point (237) via at least one of a force-locking coupling structure and a form-locking coupling structure (30, 130, 330).
 2. The operating mechanism according to claim 1, wherein the shape memory element (91) is one which becomes shorter upon heating and, reversibly, becomes longer upon cooling.
 3. The operating mechanism according to claim 1, wherein the shape memory element (91) is heatable by electric energization.
 4. The operating mechanism according to claim 1, wherein the shape memory element (91) consists of at least one wire or a bundle of wires of any desired cross-sectional shape.
 5. The operating mechanism according to claim 1, wherein the coupling element (270) is connected to the shape memory element (91) via a joined structure of an operating carriage (250) and a guide carriage (260) wherein the two carriages (250, 260) are joined by one of a magnetic coupling (30, 130) and a mechanical engagement coupling (330).
 6. The operating mechanism according to claim 1, wherein the coupling structure (30, 130) is a magnetic coupling including a first coupling element (28, 131) and a second coupling element (32, 132) and at least one of the coupling elements (31, 131, 32, 132) is one of a permanent magnet and an electromagnet.
 7. The operating mechanism according to claim 6, wherein means are provided for damping the coupling movement of the magnetic coupling (30, 130) by way of one of a rubber-elastic and a pneumatic damper (36, 236, 131).
 8. The operating mechanism according to claim 5, wherein the engagement coupling (330) includes an engagement lock structure (331) comprising an engagement pin (331) and a blocking structure (336) with a limited retaining force.
 9. The operating mechanism according to claim 8, wherein the engagement pin (331) comprises at least a double-flank hook which has a locking flank (339) and an installation flank (333), with the locking flank (339) being oriented in locking direction and having a locking flank (332) that is arranged, with respect to the locking direction, at a greater angle than the installation flank (333).
 10. The operating mechanism according to claim 1, wherein the drive arrangement (230) is fixed to one of the furniture parts (11, 21) and abuts the other furniture part (12, 11) via the coupling element (270) only at times. 